The present invention relates to a rotor used in a screw type supercharger, a screw type compressor or the like.
For example, in a screw type supercharger as shown in FIGS. 1 and 2 for generating pressurized air to be directed to an engine, a casing 1 accommodates a screw type male rotor 2 having four teeth and a screw type female rotor 3 having six teeth, which rotors 2 and 3 are intermeshingly disposed side by side. The rotors 2 and 3 have shafts 4 supported at their opposite ends by nearings 5 and are rotated by drive force transmitted from an engine to the shafts 4. Rotation of the rotors 2 and 3 causes the air from a suction port 6 at one side of the casing to be compressed and discharged into the engine through a discharge port 7 at the opposed side of the casing 1.
In the rotor 2 or 3, as shown in FIG. 3, the shaft 4 extends through a barrel 8 along the axis thereof. A blind hole 9 is opened on a wall surface of the barrel 8 and diametrically extends through the shaft 4 to the opposed wall portion of the barrel 8. A retaining pin 10 together with an adhesive is struck to be tight-fitted into the hole 9 so as to prevent the barrel 8 from being displaced relative to the shaft 4 in the axial and peripheral directions for example during the rotation of the rotor. In order to prevent the pin 10 from pulling out of the hole 9 due to a centrifugal force resulting from a high rotational speed of the rotor, a pull-out preventive pin 12 is struck into a hole 11 extending through the shaft 4 and pin 10 to join them together.
According to the rotor used in the screw type supercharger described above, the retaining pin 10 is struck for tight-fitting and the pull-out preventive pin 12 is struck to prevent the pin 10 from pulling out. It follows therefore that the hole 9 for receiving the pin 10 must be machined with a higher degree of accuracy so as to permit the tight-fit of the pin 10 and that the pull-out preventive pin 12 and the hole 11 for receiving the same are needed.
In view of the above, the primary object of the present invention is to permit thrust movement of the retaining pin toward the bottom of the retaining-pin receiving hole due to the rotation of the rotor so as to eliminate the accurate machining of the retaining-pin receiving hole for the tight-fit of the retaining pin as well as to eliminate the pull-out preventive pin and the hole for receiving the same.
The present invention will become more apparent from the following description of some preferred embodiments thereof taken in conjunction with the accompanying drawings.
The same reference numerals are used to designate similar parts throughout the figures.